My "take" is to follow the rules. Since the bases are not a full inch, you can fit 3 "ranks" just fine. You can actually fit 4.
I made this using GIMP, making the bases 25mm and the Blue and Green bubbles 1". One Inch is 25.4mm
As you can see, both A and B are within 1 inch, which means that both C and D are within 1" of a model within 1".